Directional drive control for selfstarting synchronous motors of either starting direction



MOTORS OF EITHER STARTING DIRECTION March 27, 1962 3,027,469 Patented Mar. 27, 1962 DIRECTIONAL DRIVE CONTROL FOR SELF- STARTING SYNCHRONOUS MOTORS OF EITHER STARTING DIRECTION Philip A. Sidell, West Hartford, Conn., assigner to The vide a directional drive control spring of this type which,

' while quite springy for the aforementioned purposes,

Ingraham Company, Bristol, Conn., a corporation of Connecticut Filed Sept. 28, 1959, Ser. No. 842,627 8 Claims. (Cl. 310-41) present invention is concerned :provide a spring element q which in the manner of a spring pawl cooperates with a driven motor part in permitting rotation of this part in the correct drive direction of the motor, but obstructing its rotation in the opposite direction on a wrong-directional start of the motor and thereby compelling it and the rest of the motor drive to reverse intothe correct drive direction. The spring element is vcustomarily resiliently flexed against the associated motor part so as to snap into the path of a backing shoulder thereon whenever this motor part starts in the wrong direction, with the motor drive reversing into the correct drive direction on back-'up of this shoulder against the spring element in the accustomed manner.

, While prior directional drive controls of this type' are satisfacton in most respects, they are deficient in a few important respects. Thus, the spring elements, customarily of leaf type, are usually made rather stiff for the sake of their reliable performance, resulting not only in their comparatively heavy rubbing contact with the associated motor parts and corresponding reduction of motor torque available for utility purposes, but also in rather noisy performance of these spring elements and, hence, ofthe motors themselves. Also, these spring elements are customarily arranged to act as cushioned stops which yield, morev or less, on impact with the backing shoulders of their associated motor'parts. Yet, while enhanced rebound of theassociated motor parts into correct drive direction is generally attributed to this yieldingunder-impact of the spring elements, I have found that this yielding behavior of the latter is at times conducive to hesitation in thereversal of their associated motor parts and is even responsible for occasional stalling of motors. This is due to the fact that reactive effects from this yielding-under-impact of the spring elements often extend to the initial drivers of the motors, i.e., their rotors, and occasionally cause damping, if not suppression, of the characteristic lively quiver of these rotors which is `a prime stimulus for their reversal if blocked in their movement `in the wrong direction.

lt is an objectv of the present invention to provide a directional drive control of spring-type which is structurally as simple as, and has all the other advantages of, prior directional spring-type drive controls, without having either of theirV aforementioned deficiencies, however.

It is, therefore, among the objects of the present invention to provide for a synchronous motor of random starting direction a directional drive control spring which is sufliciently stiff to remain for its reliable performance in operative relation with an associated driven motor part for the longest time andevenunder conditions of shock and vibration, yet'isv suiciently springy to have but very light rubbing contact with its associated motor part and to Jsnap quite lively into the path of a backing shoulder` on the latter onV a wrong-directional start of the same.

It is another object of the present invention to pronevertheless acts as a rigid non-yielding stop for a backing shoulder on the associated motor part when the same starts in the wrong direction, thereby to obviate any possible damping of the lively quiver of the rotor of the motor on its suddenly interrupted travel in the'wrong direction and, instead, compel instantaneous and full exertion of this rotor quiver toward rotor reversal and with it reversal of the entire motor drive.

It is a further object of the present invention to provide a directional drive control spring of this type which for its springy performance for the aforementioned purposes acts in true torsion, but is effectively locked or constrained against any torsional yield by a'backing shoulder on the associated driven motor part on its impact with the spring, thereby to compel the latter to act as a rigid Vnon-yielding stop for the Ibacking shoulder on the associated motor part as aforementioned.

Another object of the present invention is to provide a directional drive control spring of the 'aforementioned torsion-type which may conveniently be blanked from ciently stiff for its reliablefand long-time performancey even under conditions of shock and vibration, and still have the considerable springiness required for its llightrubbing contact with the associated motor partand its lively snap into the path of a backing shoulder thereon when starting in the wrong direction, yet the torsion arm will, on impact of the backingA shoulder-on the associated motor part with the follower arm, be temporarily constrained against anyyielding, torsional or otherwise.y

A'further objectof the present invention is to provide a directional drive control spring of torsion-type of which the aforementioned twisted. torsion ann rests with its entire length at all times on the support to which the spring is anchored, thereby compelling the spring to act only in true torsion in the performance of its designated function. It is another object of the present invention to provide a directional drive control springof torsion-type of which the aforementioned twisted torsion armthereof is, alternatively, further permanently bent near its anchored end so as to extend with the greater part of its length at more or less slight inclination to the support to which the spring is anchored. With this alternative spring arrangement, the torsion arm will be longitudinally liexed, rather than torsionally stressed, for normally yieldingly holding its lateral arm in follower relation with the associated driven motor part, yet the torsion arm will be depressed against the support and constrained against any yielding, torsional or otherwise, on impact between its follower arm and the backing shoulder, with the spring thus acting as the aforementioned rigid non-yielding stop for the latter on a wrong-directional start of the associated motor part.

`Other objects and advantages will appear to those skilled in the art from the following, considered in conjunction 'with the accompanying drawings.

- In the accompanying drawings, in which certain modes of carrying out the present invention are shown for illustrative purposes:

FIG. 1 is a fragmentary section through a synchronous motor with a directional drive control embodying the present invention: i i

stantially on the line 2-2 of FIG. 1;

FIGS. l3 and 4 are enlarged fragmentary sections through the same motor taken on the lines 3-3 and 4-4 respectively, of FIG. l, and prominently showing the parts ofthe featured directional drive control.

FIG. y5 is a fragmentary section similar to FIG. 4, but showing the parts of the featured directional drive con- -trol in aidifferent operating position;

A FIG. i6 is a fragmentary view of a synchronous motor with a directional drive control which embodies the invention in a r'modified manner; e

FIG. 7 is an enlarged fragmentary section through a synchronous motor with a directional drive control which embodies the present invention in a further modified man- FIG;` 8 is a View, partly in section, of this further modified drivev control as seenin the direction of the' arrow 8 inF'IG.-7f.v y

Referring'ntoft-h'e drawings, and more particularly to FIGS. l and 2 thereof, the reference` numeral 10 designates a synchronous A.C.Y lmotor having a cup-shaped casing 12 `and a platel ,1 4 which is suitably secured to the cas ing. IheivcasinglZ and'plate" 114 are :ofV non-permanent magnetic material and form part of the field of the motor. The field plate v14 is provided Iwith a circular aperture 18 and a plin'alityv of cutouts 20 therearound to define one set of spaced field poles 22. The other set of `field poles 24, which alternate' with the field poles 22 (FIG. l), are formedv byupturned tongues on another field plate 26 which at `secured to a central magnetic core 30 in the field easingY 12. Located in the field casing 12 and surrounding' the c or'e 30 is a fieldcoil 32 which on passage of an alternating current therethrough will set up periodically alternating',v instantaneous opposite polarities in the field poles' 22 and 24, as will be readily understood.

i The instantmotor further comprises a rotor 34 which inthis instance is carried by a pinion 36 on a fixed shaft 38 extending from the core 30. The rotor 34 may be of permanent or non-permanent magnetic type, and may presentl-y'be assumedf to be of permanent magnetic type with opposite poles 40 and 42 of opposite permanent polar-ities, Each of the rotorl poles 40 and 42 is provided withjan off-center notch 44 to divide it into pole sections 4 6 and 48 of different' polar widths. In thus notching the poles of the rotor" 34,l the motor becomes self-starting, as ifs` fully shown and described in the Kohlhagen Patent No. 2,677,776, dated May 4, 1954. Moreover, the rotor 34 will, on energization of the field coil 32, start in either direction, depending on the initial polarities of the field poles 22 and 24.

l The motor' pinion 36 is' presently in mesh with a gear 0 on a shaft 5 2 which is mounted with one end in the field plate |14 and presently also with its other end in a gear housing54. The pinion 36 and'gear 50 consti-tute a Vfirst speed-reduction stage'of the motor drive. Rotatable with the .gear 50 is a pinion 56 that is in mesh with an-V other gear' 58 on a shaft 60 (FIG. 1) which may suitably be journalled with its ends inthe eld plate 14 and gear Y housing 54, and which may beconsidered to be the outspring-type control element'72 and also includes arnotor-V driven member 74 withk 'which the control element 721 cooperatesv in reversingthe motor drive on a wrong-directional start thereof (FIGS. 1 to 5). The control element 72 presently comprises-an/anchor part or plate 76, a 1ongitudinal; torsion-armpart 78 which extends from the an` chorpart 76, and a lateral follower arm part 80 at the free end of the torsion arm part 78. The control or spring element 72 is conveniently blanked from flat sheet material of adequate resiliency and of uniform thickness, with the longitudintal torsion arm 78 of this blank being given a permanent longitudinal twist of presently considerably -less than a quarter turn (FIGS. 3 and 4), and in any event of less than half a turn. The torsion arm 78 may thus Y be permanently Vtwisted in the initial blanking operation or in a subsequent operation, for instance by striking this arm in known manner with a coining pressure and at places to set up permanent opposite compressive and tensile stresses requisite for its Apermanent* twist. In thus permanently twisting the torsion arm 78, the follower arm 80 isturned with the adjacent lfree end of the torsion arm 78 with which it remains coplanar thereat (FIGS. 4 and 5), with the' side edge 82 `of the' torsion arm 78 remaining in this instance in the initial plane p of the blank and the remainder of the torsion arm twisting from this plane' (FIG. 4) and thefollower arm 80 becoming disposed at an inclination to this plane.

The springl element 72 tis with its flat anchor part v76 mountedon `a fiat s unfalce of the field plate14, present- 1y by being :riveted thereto at 84am Ialso by meanset an overlying annularY shoulder 86 on the fixed sha-ft 52 (FIGS. 1, 4 `and 5). With the springelemen't 72` thus anchored to the' field plate 14, the inclined follower arm 80 extends' into follower relation with shoulderymeans 88 on the motor-driven part 74 which presently is a disc Iturning with the gearl 50 and pinion 56. 'I'ilev shoulder means 88 are presentlyar'nanged in confrontingrelation with the support plate '14, and the follower ann V80, which Vis substantiallyVA infiexible las more `rfully explained later,

is yieldingly urged, solely by resilient longitudinall torsional deflection of the torsion `arm 78, into follower engagement with these shoulder means to be depressedv tion, and as ialready mentioned, the torsion arm 78 ofv the present spring element 72 acts solely in torsion in vyieldingly ungi-ng its arm 80 finto follower engagement Y with the shoulder means 88 and permitting its resilient depression from Land snap into the path of the latter on right and wrong directional drive of the member 74, respectively. To this end, the torsion arm 78 is of an inexible Width w (FIGS. 1 and 4), but its thickness and permanent longitudinal twist are such that the follower Iarm 80 and adjacent free end of the torsion arm 78 would, in 'the absence of the member 74, form a larger `angle with the fiat surface 85 of the field plate 14 than is shown in FIG. 4. Accordingly, the member 74 with its shoulder means 88 will, through intermediation of the iniiexible follower arm 80, compel the torsion arm 78 into resilient torsional deflection (FIG. 4) with the torsion farm 78 being further torsionally loaded on each depression of the follower 'army 80 by the overriding shoulder means 88 on the drive of the disc 74 in thev right direction, presently clockwise as viewed in FIG. l and inthe direction of the 'arrow 90 inFIG. 5. The follower yarm 80 is infiexible, or substantially so, by being made shorter than theV torsion arm 78 4and by further being imade of adequate width w' (FIG. 1).. Of course, the force with which the follower arm 80 is yieldingly urged into follower eng-agement with the shoulder means 88 and, hence, also its openational sliding friction with the latter, may be varied to suit, and may be relatively small, on proper selection of the thickness and resiliency of lche material of the spring element 72, of Ithe lengths of the torsion and follower `arms 78 and 80, and of the extent of the permanent twist in the torsion arm in co1n parison tothe spacing of the member 74 from the sup- Y yielding s-top for the shoulder means 88 on being irnpacted thereby when lthe member 74 starts in the wrong direction, i.e., counter-clockwise as viewed in FIG. 1 and in the direction of the arrow 92 in FIG. 4. When such a wrong-directional start of the member 74, and hence of the motor, occurs, the follower arm 80 will snap into the path of the nearest shoulder 88 (there being presently four of them) wi-th this nearest shoulder soon impacting with the follower arm 80 and instantaneously locking or `constraining the latter against angular displacement Iabout the longitudinal axis of the torsion arm 78. The follower larm 80 is thus constrained against angular displacement on impact with the nearest shoulder 88 by being presently wedged against the latter and the adjacent oifset face 94 of the member 74 in lthe manner shown in dot-and-dash lines in FIG. 4. Of course, with the inllexible follower arm 80 thus constrained against angular displacement by the impacting shoulder 88', the torsion arm 78 is prevented from yielding in the only manner of which it is capable, namely torsionally, with the result that the spring element 72 acts indeed as a rigid non-yielding stop for the nearest shoulder 88 on impact therewith, and the ensuing yabrupt stop of the latter forces the motor drive, including the rotor 34, into the same abrupt stop. The rotor 34, being thus stopped positively and abruptly on a wrong-directional start, will by its undampened lively action and under the further compellent influence of the periodically changing polarities of the field poles 22 and 24, assuredly swing without hesitation into the opposite direction and thus reverse the motor drive into the right direction.

It follows from the preceding that the arrangement of the spring element 72 is such as to preclude any operational resilient longitudinal liexure of any part thereof, and to permit only resilient longitudinal torsional deflection of the torsion arm 78. The components of any and all forces acting on the arm 80 by virtue of its follower engagement with the member 74, and having any tendencies longitudinally to flex the torsion arm S0, are rendered ineffective by making the torsion arm 78 of the described inliexible width w and by having the torsion arm normally rest with its side edge 82 against the field plate 14. By making the torsion and follower arms 78 and 80 of considerable lengths, but safely within limits to preclude their longitudinal flexure when in action, the yielding force with which the arm 80 is urged into follower engagement vvith the member 74, and hence also its operational sliding friction therewith, may be kept relatively small despite the inflexible width of the torsion arm 78, with the result that no more than a negligible part of -the -motor torque is used up by the directional drive control a-nd the latter performs with inappreciable, if any, noise.

The yielding force with which the follower ann of the spring element is urged into follower engagement with the associated motor-driven member may be even further reduced. Thus, FIG. 6 shows a modified directional drive control 70a of which` the torsion arm 78a of the spring element 72a on the iield plate 14a is of such narrow width w as conceivably longitudinally to flex widthvvise on impact of a shoulder 88a on lthe associated motordriven member 74a with the follower arm 80a on a wrong-directional start of the former. However, this torsion arm 78a of exceptionally small width is at its free end effectively backed with its side edge 82a against a xed stop 100 which may conveniently be struck from the field plate 14a, so that any force on the follower `arm Sila tending longitudinally to flex the torsion arm 78a widthwise is entirely taken up by this stop 100 before it may exert itself 'on the torsion arm. Of course, with this modified directional drive control 70a, involving a torsion yarm of exceedingly narrow width and a xed backing stop at its free end, the yielding force with which the follower arm 80a is urged into engagement with the associated motor-driven member 74a, and also the operational sliding friction between them, may be at a minimum.

While in the described directional drive controls 70 and 79a the torsion arm of the spring element normally rests with one side edge against the field plate and, hence, is operationally longitudinally resiliently inflexible thereagainst, FIGS. 7 and 8 show a further modified directional drive control 70lb of which the torsion arm 78h of the spring element 72b is longitudinally resiliently flexible against the field plate 14h. In fact, and as shown in FlG. 7, the torsion arm 78b may be longitudinally resiliently iexed away from the support plate 1412 suiciently to act solely in longitudinal resilient flexure in yieldingly retaining its inliexible arm b in follower relation with the motor-driven member 74b. The spring element 72b may thus be exactly like the spring element 72 (FIG. 3), except that the present spring element 472b may be permanently bent at for permanent deiiection of the torsion arm 78b away from the eld plate 14h. Thus, with the member 74b driven in the correct direction as represented by the arrow 106 in FIG. 7, the torsion arm 78h will longitudinally hex toward and away from the field plate 14b when the shoulder means 88h override the follower arm 80h. However, onr a wrong-directional start of the member 74b in the direction of the arrow 108 in FIG. 8, the follower arm Stlb will snap into the path of the nearest shoulder means 8817 and be impacted thereby. As a result of this impact as shown in FIG. 8, the permanently twisted torsion arm 78b will be longitudinally flexed against the iield plate 14b and its follower arm Stib will then be locked against angular displacement to leave the spring element 72b without any yield, torsional or flexurewise. The spring element 72b will thus act as a positive stop for the shoulder means 88b on a wrongdirectional start of the member 74b, but will act in longitudinal flexure for the rest of its performance.

The invention may be carried out in other specific ways than those herein set forth without departing from the spirit and essential characteristics of the invention, and the present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

What is claimed is:

l. A directional drive control for a self-starting synchronous motor of reaction-type, comprising a driven member starting in either direction; a fixed support member, said members having surfaces facing each other; a shoulder on and projecting from said surface of one of said members; a substantially straight longitudinally twisted leaf spring of greater Width than thickness having one end lying at on said surface of the other member and anchored thereto, with the rest of said leaf spring having freedom for at least torsional resilient deflection and the other end thereof being in the path of said shoulder, the twist of said leaf spring being sufficient to have said other end thereof widthwise inclined to said surfaces and be with its side edge thereat nearest said surface of said one member in operative alignment with said shoulder so as to be resiliently depressed from and snapped into the path of the latter on rotation of said driven member in the right and wrong directions, respectively, and said surfaces being spaced so that said other spring end will be wedged between them by said shoulder on impact therewith.

2. A directional drive control for a self-starting synchronous motor having a rotor with a power start in either direction, comprising a fixed support; a rotary member driven by the rotor and having a face confronting said support and a shoulder projecting from said face; and a substantially straight longitudinally twisted leaf spring of greater width than thickness having one end lying Iflat on said support and anchored thereto, with the Vrest of said leaf spring having freedom for at least torsional resilient deection and the other end thereof being spaced so that said otherspring end will be wedged between them by said shoulder on impact therewith.

3. Ay directional drive control as set forth in claim 2, in which said leaf spring normally rests with its other side edge on said support so that said leaf spring has freedom for onlyv torsional resilient deflection.

Y 4. A directional drive control as set forth in claim 2, in which saidleaf'sprinlg is normally ilexed away from rsaid support so as to have alsoffreedom for resilient longitudinal flexure against the latter.

7.5. A directional ldrive control as set forth in claim 2,

in which saidV leaf spring is normally flexed awayfrornY said support suiciently to respond only in resilient longi- 8 tudinal'flexure to depression of said other end'th'ereof by said shoulder. y

6. A directional drive control vas set forth in claim 2, in which said side edge of said other spring endis formed by an inflexible lateral arm on said leaf spring.

7. A directional drive control as set forth in claim 6, in which said side edge of said other spring end is provided by an inexible lateral arm on'said leaf spring formed integrally with the latter and being coplanar with said other end thereof.

8. A directional drive control as set forth Vin claim 6, in which said side edge of said other spring end is formed by an inflexible lateral arm on said leaf spring, and the latter is of such small width'as to be Widthwise resiliently flexible for minimum resistance to its torsional resilient deflection, and there is provided on said support a stop backing the other side edge of said other spring end to prevent Widthwise flexure of said leaf spring on impact with said shoulder.

References Cited in the file of this patent UNITED STATES PATENTS 

